In recent years, with advancement of miniaturization of semiconductor devices using silicon wafers or the like, a possibility has been pointed out that very fine particles of approximately 10 to 20 nm, which have not brought question conventionally, affect device performances.
To detect particles on a surface of each wafer, an inspection technique using scattered light is generally used. Since the particle detection sensitivity provided by a measuring machine using the scattered light is determined by a ratio of a defect signal and its background noise, when the background noise called haze is high, the S/N ratio is lowered, and accurate measurement cannot be performed. It is known that, since scattered light due to surface roughness of a wafer is detected by a haze, the haze has a close relationship with the surface roughness, and reducing the surface roughness decreases the haze.
A typical technique to suppress the haze includes controlling cleaning conditions which is performed after final polishing of wafers. For example, lowering the cleaning temperature of SC1, which is a mixed solution of NH3 and H2O2, suppresses the alkaline etching function on a wafer surface, and reduces the surface roughness, consequently decreasing the haze.